diff --git a/relay/channel/claude/relay-claude.go b/relay/channel/claude/relay-claude.go
index 046ccfe6..6356cd35 100644
--- a/relay/channel/claude/relay-claude.go
+++ b/relay/channel/claude/relay-claude.go
@@ -442,10 +442,7 @@ func StreamResponseClaude2OpenAI(claudeResponse *dto.ClaudeResponse) *dto.ChatCo
 	tools := make([]dto.ToolCallResponse, 0)
 	fcIdx := 0
 	if claudeResponse.Index != nil {
-		fcIdx = *claudeResponse.Index - 1
-		if fcIdx < 0 {
-			fcIdx = 0
-		}
+		fcIdx = *claudeResponse.Index
 	}
 	var choice dto.ChatCompletionsStreamResponseChoice
 	if claudeResponse.Type == "message_start" {